Nancy Pelosi has made headlines once more after securing a fourth term as Speaker of the House of Representatives. It marks a new chapter in her nearly 50-year political career with the Democrats - and perhaps her greatest challenge yet.

With Kamala Harris about to be the country's first female vice-president, Pelosi can no longer claim the mantle of most powerful woman in US politics.

But the 80-year-old will play a critical role in advancing the agenda of the new president.

That means there's no time to dwell on her personal disappointment over November's election - she takes charge of a shrinking majority in the lower chamber.

And on Sunday, she was only narrowly re-elected as Speaker, following defections from a handful of Democrat colleagues.

Instead, her coming term must demonstrate all the Pelosi qualities that both rally her supporters and alienate her many detractors.

Her legislative acumen, her ability to keep a restless party united when it matters and her instinct for political theatre (more on that sarcastic clap later).

Raised in a political family
Republicans have typically painted Ms Pelosi as a "San Francisco liberal" enamoured with big government and far to the left on social issues.

But her roots are from a more practical style of politics on the other side of the continent.

She grew up in a political family, youngest of seven children in the gritty East Coast city of Baltimore, Maryland, where her father was mayor.

She went to college in nearby Washington where she met and eventually married financier Paul Pelosi.

They first moved to Manhattan, and then San Francisco, where Ms Pelosi started as a housewife.

She had five children - four daughters and a son - in the space of six years.

The start of something big
In 1976 she became involved in politics, using her old family connections to help California Governor Jerry Brown win the Maryland primary as he ran for president.

She then rose through the state's Democratic Party ranks, eventually becoming its chair and then winning a seat in Congress in 1988.

In the House she worked her way up again. Because she represented a portion of the city with a large gay community, she made increasing Aids research funding a priority.

In 2001, she ran for House minority whip, which is vote-counter and second in command of the party in the House, and won a narrow victory.

The next year she moved up to minority leader, which means leading the party in the House but in opposition.

Reaching the top
She was one of the highest-profile, most outspoken opponents of the US invasion of Iraq in 2003.

This stand was vindicated and paid dividends in 2006 when the Democrats took control of the House for the first time in 12 years.

She was elected by her party to be Speaker of the House, becoming the first woman in that role in US history.

Four years later, Democrats lost control of the lower chamber of Congress.

Despite the setback Ms Pelosi defeated several challenges within her own ranks, to take the gavel once more at the helm of a resurgent party in 2018.

What does a Speaker do?
Speaker of the House is the one congressional job detailed in the US Constitution. It is second in line for the presidency, behind only the vice-president.

Its massive office, in the Capitol rotunda, reflects the prestige of the job, with its own balcony looking out toward the Washington Monument.

The majority party in the House has virtually unfettered control over the legislative process.

The speaker and her deputies and committee chairs determine what bills are considered and voted on. They set the agenda and decide the rules governing debate.

If a speaker can keep her majority in line, the legislative process in the House can purr like a well-tuned machine.

From 2009 to 2011, Pelosi's chamber enacted an $840bn stimulus package in the aftermath of the 2008 economic collapse.

She also pushed hard to get the Affordable Care Act, which became the defining battle of the Barack Obama presidency, through the House and on to the president's desk.

Pelosi's biggest moment
She faced very different circumstances when she returned to the speaker's chair in 2018.

By then she was a lightning rod for Republican anger - in their eyes, representing the coastal elites pushing a big-spending, radical platform.

During the 2018 midterms campaign, Republican incumbent David Brat mentioned Nancy Pelosi and her "liberal agenda" 21 times in one debate.

The move backfired for him - and his party - as Democrats swept to a historic win in the House.

But this time she had President Donald Trump as well as the wily Senate Majority Leader Mitch McConnell as obstacles. So any bills her party got through the House didn't go any further.

In viral terms, her big moment was her sarcastic #PelosiClap during Trump's State of the Union speech a month after she took office. It still lives on as a popular gif.

Most controversially that same night, she also ripped up Trump's speech in front of the TV cameras. Accused of disrespect, she later defended the move, calling his words a "manifesto of mistruths".

Taking on Trump
Pelosi was initially reluctant to lead only the third impeachment of a US president.

But as more emerged in 2019 of Trump's dealings with Ukraine she eventually said it was an abuse of power that could not be ignored.

He was accused of pressing Ukraine to dig up damaging information on Joe Biden, and using military aid as leverage but was acquitted in the Republican-controlled Senate.

Some of those in her own party who were openly calling for her removal in 2018 have since been impressed by the way she has taken on President Trump.

As well as some testy exchanges in the Oval Office, she has scored some big legislative wins against him over the border wall funding and a government shutdown.

A hollow victory
Expectations were high for Democrats to increase their House majority in 2020. But they ended up losing members of Congress instead - more than a dozen net losses.

Given the presence of Donald Trump on the ticket to rally Republicans, it was always optimistic for them to expect to improve on their 2018 landslide.

But the setback will make things harder for Pelosi as she fights a continuous battle to keep the left-wing of her party happy.

The BBC's Anthony Zurcher says this coming term could present her with her biggest political challenge yet.

"She must find a way to cajole her razor-thin majority into continued action, with the hopes that Democrats either take back the Senate on Tuesday or convince a handful of Republican moderates to form a deal-making coalition in Congress.

"Pelosi has been seldom outmanoeuvred in parliamentary procedure and is unrivalled in her ability to keep her party from breaking ranks - either from the left or the middle.

She'll have to keep it up, with little margin for error, if she wants to help Joe Biden get his new administration off to a successful start."